Abstract

Isotopic analysis of human blood and liver and muscle tissue indicates that each individual bears a long-term iron (Fe) isotope signature in the blood. Blood and tissue differ slightly in isotopic composition and are depleted by up to 2.6 per mil in 56Fe relative to 54Fe when compared to dietary Fe. The56Fe/54Fe isotope ratio in the blood of males is, on average, lower by 0.3 per mil than that of females. These results suggest that Fe isotope effects in the blood reflect differences in intestinal Fe absorption between individuals and genotypes.

↵* To whom correspondence should be adressed. E-mail: thomas.walczyk{at}ilw.agrl.ethz.ch